JPH06102820B2 - Method for producing manganese-aluminum-carbon alloy magnet - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for manufacturing a permanent magnet, and more particularly, for multipolar magnetizing with a polycrystalline manganese-aluminum-carbon (Mn-Al-C) alloy magnet. The present invention relates to a method for manufacturing an Mn-Al-C alloy magnet.

(Prior Art) An alloy for Mn-Al-C magnets has 68 to 73 mass% (hereinafter simply expressed as%) of Mn and (1 / 10Mn-6.6) to (1 / 3Mn-22.2)%.
The alloys for multi-component magnets, which are composed of C and the balance Al and contain no additional element other than impurities, and quaternary or more multi-element magnets containing a small amount of additional elements are known and are collectively referred to. . Similarly, alloying Mn-Al-C based magnets, face-centered tetragonal (tau phase, Ll ₀ type ordered lattice) is mainly ferromagnetic phase consists of tissue are those containing C as the essential constituent elements A ternary system alloy containing no additional element other than impurities and a quaternary or more multi-component magnet alloy containing a small amount of additional element are known and are collectively referred to.

Conventionally, the manufacturing method has been one in which the outer periphery of a hollow body billet made of an alloy for Mn-Al-C magnets is constrained by an outer die, and compression processing is performed by a punch whose compression surface is a flat surface. (JP-A-58-192306).

(Problems to be Solved by the Invention) According to the above-described conventional manufacturing method, the billet is subjected to substantially the same compressive strain on both the inner and outer peripheral portions thereof. , Second
It becomes a substantially straight line in the radial direction like the line A in the figure.

Therefore, as shown in the same figure in this state, for example, even if it is attempted to magnetize S and N on the inner circumference, the ideal semi-circular B line which is the ideal easy magnetization direction array is too much. Since the arrangement of the easy magnetization direction is different, a strong magnetic force could not be obtained even when the magnetizing work was performed.

Therefore, in the above-mentioned conventional example, before the S and N are magnetized on the inner circumference, the inner circumference of the compressed billet is compressed again so that the easy magnetization direction array is substantially semicircular as shown by line B in FIG. And then magnetized the inner circumference.

However, in the conventional case, in order to obtain such a substantially semicircular easy magnetization direction array, the inner circumference or the outer circumference of the billet must be compressed again after the compression of the billet, and the workability is poor. there were.

Therefore, an object of the present invention is to make it possible to easily obtain a substantially semi-circular array of easy magnetization directions in the case of magnetizing S and N on the outer peripheral portion of the billet.

(Means for Solving the Problems) Then, in order to achieve the above object, the present invention provides a hollow body-shaped billet made of a pre-anisotropic polycrystalline manganese-aluminum-carbon magnet alloy. 530 ~ 830
At a temperature of 10 degrees, with the outer periphery of the billet restrained by an outer mold,
Moreover, at least a part of the inner circumference is configured to be axially compressed by a punch, and the compression surface of the punch is provided with an inclination that approaches the end of the billet from the outer peripheral surface toward the inner peripheral surface. The billet is compressed in the axial direction so that the inner part of the billet has a larger compressive strain than the outer part.

(Operation) With the above-mentioned structure, the billet is axially constrained by a punch while the outer periphery of the hollow body billet made of a pre-anisotropic polycrystalline manganese-aluminum-carbon magnet alloy is constrained by an outer die. When compressed to, since the compression surface of the punch has an inclination approaching the end of the billet from the outer peripheral portion toward the inner peripheral portion, the billet has a compressive strain greater than the compressive strain of the outer peripheral portion, As a result, an approximately semi-circular easy magnetization direction array is easily formed by one-time compression on the inner circumference of the billet after compression, and this makes it strong when S and N are magnetized on the outer circumference of the billet. That is, a strong magnetic force can be obtained.

(Example) Hereinafter, the Example of this invention is described with reference to drawings.

FIG. 1 is a sectional view showing an example of a processing apparatus for carrying out one embodiment of the present invention, and FIGS. 1 (a) and 1 (b).
3A and 3B are cross-sectional views of a main part showing states before and after processing, respectively, in which the cylindrical billet 1 is compression processed by the upper punch 2, the lower punch 3 and the outer die 4. As shown in FIG. 1 (a), the compression surfaces of the upper punch 2 and the lower punch 3 are conical surfaces having an inclination approaching the end of the billet 1 from the outer peripheral surface toward the inner peripheral surface. . By these upper and lower punches 2 and 3, the cylindrical billet is compressed in the axial direction,
A mortar-shaped cylindrical billet 5 shown in FIG. 1 (b) is obtained in which the height of the outer peripheral portion is higher than the height of the inner peripheral portion. That is, the billet 5 is obtained by subjecting the billet 1 to compression processing so that the compression strain in the inner peripheral portion is larger than the compression strain in the outer peripheral portion. The compressive strain means strain in the axial direction of the billet.

Next, more specific examples according to the present invention will be described.

That is, in the composition, 69.4% manganese Mn, 29.3% aluminum Al, 0.5% carbon C, 0.7% nickel Ni, and
After 0.1% titanium Ti was melted, a cylindrical billet having a diameter of 50 mm and a length of 40 mm was cast. This cylindrical billet was heated at a temperature of 1100 ° C. for 2 hours, air-cooled to a temperature of 600 ° C., held as it was for 30 minutes, and then heat-treated to cool to room temperature. next,
Using a lubricant, extrusion processing was performed at a temperature of 720 ° C to obtain a bar material having a diameter of 32 mm and a length of 98 mm. This rod is cut and cut to form a cylindrical billet 1 with both outer diameters of 30 mm, inner diameter of 20 mm, and length of 20 mm and flat end faces. Then, this cylindrical billet 1 is lubricated with a lubricant as shown in FIG. The outer punch 4 having an inner diameter of 30 mm shown is used to constrain the outer circumferential surface, and the inner punch is free, and the upper punch 2 and the lower punch 3 each having an end surface composed of a conical surface having an inclination angle α of 20 ° are used. Cylindrical billet 1 at a temperature of 680 ℃
The compression processing was performed until the length of the outer peripheral portion became 13.3 mm.

The inner diameter of the compressed billet 5 was cut to 18 mm, and the inner peripheral surface was multi-polarized with 18 poles using a magnetizing device, and the surface magnetic flux density was measured with a Hall element.

For comparison, the extruded rod described above was cut and cut into a cylindrical billet 1 having an outer circumference of 30 mm, an inner circumference of 20 mm, and a length of 20 mm. This cylindrical billet is lubricated with a die whose compression surface is flat, and the length of the cylindrical billet 1 is 1
The surface magnetic flux density was measured by performing compression processing to 3.3 mm, further cutting the inner peripheral surface to the same size as the above, and magnetizing.

As a result of comparing these two values, the surface magnetic flux density of the magnet obtained by the method of the present invention was 1.2 times the surface magnetic flux density of the magnet prepared for comparison.

(Effects of the Invention) As described above, the present invention is based on a polycrystal that is anisotropy in advance.
Hollow body billet made of Mn-Al-C magnet alloy is compressed in the axial direction by a punch while the outer circumference of the billet is constrained by an outer die. The compression surface of the punch is from the outer circumference to the inner circumference. Since the billet has an inclination that approaches the end of the billet, the compressive strain of the billet becomes greater than the compressive strain of the billet, and as a result, the billet after compression has a substantially A semi-circular easy-direction array is easily formed by one-time compression, and a strong magnetic force can be obtained by magnetizing S and N on the inner circumference of the billet.

[Brief description of drawings]

1 (a) and 1 (b) are sectional views showing an example of a processing apparatus for carrying out an embodiment of the present invention, and FIG. 2 is a plan view showing an easy magnetization direction array. 1,5 ... Billet, 2,3 ... Punch, 4 ... Outer mold.

Claims (3)

[Claims] 1. Pre-anisotropic polycrystalline manganese-
A structure in which a hollow billet made of an aluminum-carbon alloy magnet is axially compressed by a punch at a temperature of 530 to 830 ° C while the outer periphery of the billet is constrained and at least a part of the inner periphery is free. And, the compression surface of the punch is provided with an inclination that approaches the end of the billet from the outer peripheral surface toward the inner peripheral surface, so that the compression strain of the inner peripheral portion of the billet is larger than the compression strain of the outer peripheral portion. A method for producing a manganese-aluminum-carbon alloy magnet, which comprises subjecting a hollow body to compression processing in the axial direction. 2. The billet is composed of a polycrystalline manganese-aluminum-carbon alloy magnet having an axis of easy magnetization in the axial direction of the hollow body, and the compressive strain is 0.05 or more in absolute value of logarithmic strain. A method for producing a manganese-aluminum-carbon alloy magnet according to the range (1). 3. The billet has an axis of easy magnetization parallel to a plane perpendicular to the axial direction of the hollow body, is magnetically isotropic in the plane, and is parallel to the axial direction and the plane. The method for producing a manganese-aluminum-carbon alloy magnet according to claim (1), comprising a polycrystalline manganese-aluminum-carbon alloy magnet which is anisotropic in a plane.